The U.S. Centers for Disease Control and Prevention now says wearing two masks offers more protection against COVID-19 than one mask.

In an experiment using artificial heads spaced 6 feet apart, the CDC said one mask, either surgical or cloth, blocked about 40% of coronavirus-sized particles, but a cloth mask worn on top of a surgical mask blocked 80%.

However, the study only used one kind of surgical mask and one type of cloth, making it unclear if the same results would be achieved with different materials.

Information about masks has changed over the course of the pandemic. At the outset, health officials told Americans not to wear masks, including a year-old tweet from then-Surgeon General Jerome Adams saying, "Seriously people - STOP BUYING MASKS!"

In March, Dr. Anthony Fauci said there was "no reason" to wear masks, though he changed course a short time later.

Later, health officials recommended masks when social distancing could not be maintained. That later changed to recommending wearing masks while in public.

A recent University of California survey found that only about half of Americans regularly wear masks when in close contact with people outside their households.

上一篇：voacorr 2021-02-10 Anti-Coup Protests in Myanmar Continue Despite Increasing Crackdown

下一篇：voacorr 2021-02-10 Impeachment Prosecutor_ Trump Was 'Inciter in Chief'